Data and/or PowerSwivel

ABSTRACT

In one aspect of the invention, a swivel for use in a drilling operation comprises a body with a central bore adapted for threaded connection to a tool string component. At least one electrically conductive medium is rotationally supported within the bore and adapted to rotate with respect to an electrically conductive receiver that is rotationally fixed to and disposed within the body. The electrically conductive medium and the receiver are in electrical communication through an electrically conductive arm that is rotationally fixed to the electrically conductive medium and at least partially disposed within an electrically conductive fluid disposed within a reservoir. The reservoir comprises a rigid shape that is partially filled by the conductive fluid. A least one rotary seal is disposed intermediate the reservoir and the electrically conductive medium. The rigid shape of the reservoir is adapted to prevent the conductive fluid from accumulating around the rotary seal.

BACKGROUND OF THE INVENTION

The present invention relates to the field of data and/or power transmission. More specifically, it relates to the field of apparatus for transmitting data and/or power from downhole tool strings to stationary equipment, such as surface equipment.

Downhole tool strings, such as drill strings, have become increasingly versatile in the last half century. In addition to traditional oil, gas, and geothermic exploration and production purposes, tubular tool strings are often used for what is known as horizontal directional drilling to install underground power lines, communication lines, water lines, sewer lines, utility lines, and gas lines. This sort of downhole drilling is particularly useful for boring underneath roadways, waterways, populated areas, and environmentally protected areas.

The increased versatility of downhole drilling with tool strings has led to a higher demand for apparatus that are able to transmit a power signal to downhole equipment as well as transmit data and/or power between downhole tools and surface equipment. Hence, several different approaches to solving the problem of transmitting an electrical signal across the joints of a tool string have been developed and are known in the art.

U.S. Pat. Nos. 6,670,880 and 6,717,501 to Hall et al., both of which are incorporated herein by reference for all that they disclose, teach of a system wherein tubular components are coupled at threaded joints and comprises a signal transmission system in the tool string. Other downhole telemetry systems are disclosed in U.S. Pat. No. 6,688,396 to Floerke et al and U.S. Pat. No. 6,641,434 to Boyle et al, which are also herein incorporated by reference for all that they contain.

Optimally, a system for transmitting power or data between surface equipment and downhole tools in a tool string should be transparent to the tool string operator or crew, as time delays introduced by a complicated telemetry system may represent a significant amount of money.

The use of data swivels for transmitting real-time data to stationary equipment has been disclosed in the art. Some examples of Mercury-type rotating electrical contacts that may be used in data swivels are found in U.S. Pat. No. 2,702,890 to Hildebrandt; U.S. Pat. No. 3,021,496 to Kenyon; U.S. Pat. No. 3,022,479 to Rohrbach; and U.S. Pat. No. 3,957,330 to Roscoe et al; as well as examples of inductive swivels for use in downhole applications are disclosed in U.S. Pat. Nos. 7,098,802 and 7,193,527 both to Hall et al; each of which is herein incorporated by reference for all that it contains.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a swivel for use in a downhole drilling operation comprises a body with a central bore adapted for threaded connection to a tool string component. At least one electrically conductive medium is rotationally supported within the bore and adapted to rotate with respect to an electrically conductive receiver that is rotationally fixed to and disposed within the body. The electrically conductive medium and the receiver are in electrical communication through an electrically conductive arm that is rotationally fixed to the electrically conductive medium and at least partially disposed within an electrically conductive fluid disposed within a reservoir. The reservoir comprises a rigid shape that is partially filled by the electrically conductive fluid. At least one rotary seal is disposed intermediate the reservoir and the electrically conductive medium. The rigid shape of the reservoir is adapted to prevent the conductive fluid from accumulating around the rotary seal.

The swivel may comprise a plurality of reservoirs, electrically conductive arms, or electrically conductive media. The reservoir may be disposed circumferentially around at least a portion of the electrically conductive medium. The electrically conductive medium may comprise and electrically conductive core that may be surrounded by a dielectric material selected from the group consisting of alumina, ferrite, polycrystalline diamond, carbon, polymers, plastics, rubber, latex, and/or oxides of Mg, Al, Si, Yb, Ca, Be, Sr, Ns, Sm, Er, Eu, Sc, La, Gd, Dy, Tm, ceramics and combinations thereof. The electrically conductive medium may comprise a coaxial cable, a pair of twisted wires, a biaxial cable, a triaxial cable, insulated copper wires, or combinations thereof. An electrically conductive shield of a coaxial cable may be in electrical communication with a first reservoir and an electrically conductive core of the coaxial cable may be in communication with a second reservoir. A channel may extend from a first reservoir to second reservoir or to a second end of the first reservoir.

The receiver may be an electrically conductive portion of the body or may be in electrical communication with an electrical device. The electrical device may be a computer, a data processing unit, a data storage unit, or combinations thereof. The swivel may be in electronic communication with a downhole telemetry system. The electrically conductive fluid may comprise mercury, indium, an aqueous solution, liquid metal, gallium, eutectic mixtures, mixtures thereof, compositions thereof, or a combination thereof.

The rigid shape of the reservoir may be adapted to retain the conductive fluid within the reservoir between the receiver and the electrically conductive arm and away from the at least one rotary seal when a central axis of the reservoir is parallel to the ground and when it is not parallel to the ground. The rigid shape may comprise a generally cylindrical geometry that is coaxial with the body and comprises inner and outer diameters. The rotary seal may comprise at least one o-ring, gasket, adhesive, washer, fastener, back-up or combinations thereof. The reservoir may comprise a flow restrictor proximate the rotary seal. A volume of the reservoir may be less than 50% filled by the electrically conductive fluid. In some embodiments of the invention the reservoir may comprise an internal separator wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of an embodiment of a drill string in a horizontal drill well.

FIG. 2 is a perspective diagram of an embodiment of data swivel coupled to a tool string component.

FIG. 3 is a cross-sectional diagram of an embodiment of a data.

FIG. 4 is a cross-sectional diagram of an embodiment of a data swivel rotated 45 degrees from the embodiment disclosed in FIG. 3.

FIG. 5 is a cross-sectional diagram of an embodiment of a data swivel that is orthogonal to the embodiment disclosed in FIG. 3.

FIG. 6 is a cross-sectional diagram of another embodiment of a data swivel.

FIG. 7 is a cross-sectional diagram of another embodiment of a data swivel.

FIG. 8 is a cross-sectional diagram of another embodiment of a data swivel.

FIG. 9 is a cross-sectional diagram of another embodiment of a data swivel.

FIG. 10 is a cross-sectional diagram of another embodiment of a data swivel.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

A tool string may be a drill string 100. The drill string 100 may drill a bore hole 101 in subterranean formation 102 in a horizontal direction such as those used to install utility lines or for coal methane drilling. In other applications of the present invention, the tool string may be for use in deep oil and gas drilling, geothermal drilling, or various types of exploration. In the embodiment of FIG. 1, a rig 103 is placed at the surface and is angled such that the drill string 100 penetrates the surface at a non-perpendicular angle. As the drill string 100 advances, the bore hole 101 gradually becomes generally parallel to the surface and then eventually returns to the surface at a predetermined location, at which time a back reamer may be attached to the drill string 100 and pulled back through the bore hole 101 in order to widen the hole for pipe and other tools to be inserted. Cables such as fiber optic or metal cables may also be attached to the drill string 100 as it is pulled back through the bore hole 101.

To accomplish horizontal directional drilling, the drill string 100 may comprise a steering mechanism The steering mechanism may allow the drill string 100 to change direction while drilling, which may allow the drill string 100 to avoid obstacles such as bodies of water or paved surfaces. Surface equipment, which may be part of the rig 103, may allow drill string operators to observe and manually control the direction of the bore hole 101.

Downhole tool string components may comprise drill pipes, jars, shock absorbers, mud hammers, air hammers, mud motors, turbines, reamers, under-reamers, fishing tools, steering elements, MWD tools, LWD tools, seismic sources, seismic receivers, pumps, perforators, packers, other tools with an explosive charge, mud-pulse sirens, or combinations thereof Downhole LWD tools may be located in a bottom hole assembly or along the length of the downhole tool string 100. The tools may be inductive resistivity tools, sensors, drill bits, motors, hammers, steering elements, links, jars, seismic sources, seismic receivers, and other tools that aid in the operations of the downhole tool string 100. In order to provide power to downhole tools while drilling, the drill string 100 may comprise an electrical transmission system. An example of an electrical transmission system that may be compatible with the present invention is disclosed in U.S. patent application Ser. Nos. 11/428,445; 11/559,461; 11/737,178; and 11/693,909 to Hall, et al., all of which are herein incorporated by reference for all that they contains. Also in some embodiments, the telemetry system disclosed in U.S. Pat. No. 6,670,880, which is also inhere incorporated by reference for all that it contains, may also be compatible with the present invention. Sensors may sense gamma rays, radioactive energy, resistivity, torque, pressure, temperature, or other drilling dynamics measurements or combinations thereof from the formation being drilled. Other sensors may be useful downhole such as, inclinometers, thermocouplers, accelerometers, and imaging devices. To transmit data in real-time from the tool string to surface equipment or data and/or power to downhole equipment swivel may be employed.

Referring now to FIG. 2, a data swivel 201 may facilitate the transfer of data power and/or electricity between a rotating drill string 100 and the stationary rig 103 on the surface. In some embodiments the swivel 201 may be disposed downhole. The swivel 201 may be in electronic communication with a downhole telemetry system such as the systems discloses in U.S. Pat. Nos. 6,670,880 and 6,717,501 to Hall et al. In FIG. 2 the data swivel 201 is electrically connected to the drill string 100 by a tool string component 202 via an NPT connector 207. In the present embodiment the tool string component 202 connects with the drill string 100 and with a drilling fluid supply pipe 203. The swivel 201 also comprises a SubMiniature version A (SMA) connector 204 connected to a data cable 205, which may connect to an electrical device such as a computer, data processing unit, data storage unit, or combinations thereof. A rotary rod 206 may be attached to the swivel 201 and may assist in connecting the swivel 201 to the NPT connector 207. The tool string component 202 and the drill string 100 may be connected such that the drill string 100 may rotate while being rotateably connected to the component 202.

FIG. 3 discloses a cross-sectional diagram of a data swivel 201 in accordance with the present invention. Data swivel 201 comprises a body 301 that is adapted for threaded connection with tool string component 202 via an NPT connector 207 and a swivel nut 302. The body 301 comprises a central bore 303 in which an electrically conductive medium 304 is rotationally supported. The medium 304 is adapted to rotate with respect to an electrically conductive receiver 305 that is rotationally fixed to and disposed within the body 301. In the current embodiment the electrically conductive medium 304 is a coaxial cable, but the medium 304 may comprise a coaxial cable, a pair of twisted wires, a biaxial cable, a triaxial cable, insulated copper wires, or combinations thereof. The medium 304 in the present embodiment comprises an electrically conductive core 306 that is surrounded by a dielectric material 307. The dielectric material 307 may be selected from the group consisting of alumina, ferrite, polycrystalline diamond, carbon, polymers, plastics, rubber, latex, and/or oxides of Mg, Al, Si, Yb, Ca, Be, Sr, Ns, Sm, Er, Eu, Sc, La, Gd, Dy, Tm, and combinations thereof. The dielectric material 307 may be surrounded by a shield 308 and by a stainless steel conduit 309. The shield 308 and conduit 309 may help to form electrical connections between adjacent components at downhole junctions of the components. The shield 308 and conduit 309 may also protect the electrical signal as it passes from one component to another. This may provide the advantage of keeping the power and/or data signals undistorted while they are traveling from component to component. In some embodiments of the invention electrical power may be transferred downhole via the core 306 and data may be transferred back uphole via the conduit 309 or shield 308. Alternatively, power may be transferred downhole via one medium 304 and data may return uphole via a separate medium 304.

An electrically conductive arm 310 is rotationally fixed to the conduit 309 and extends from the medium 304 into an electrically conductive fluid 311 disposed within a reservoir 312. In the present embodiment the reservoir 312 is disposed circumferentially around a portion of the medium 304. Whenever the arm 310 is at least partially disposed within the fluid 311, the medium 304 and the receiver 305 may be in electrical communication. The reservoir comprises a rigid shape 314 that is partially filled by the electrically conductive fluid 311. In some embodiments of the invention a total volume of the reservoir 312 may be less than 50% filled by the fluid 311. In some embodiments a non-conductive pressurized lubricant may fill some or all of the reservoir's volume that is not filled by the fluid 311. A plurality of rotary seals 313 are disposed intermediate the reservoir 312 and the medium 304 and are designed to prevent the fluid 311 from going between the reservoir 312 and the medium 304. The reservoir's rigid shape 314 is adapted to prevent the fluid 311 from accumulating around the rotary seals 313.

The swivel 201 may comprise a plurality of reservoirs 312 or a plurality of arms 310. In FIG. 3 two reservoirs 312 are shown disposed within the body 301. A separate electrically conductive arm 310 is disposed within each reservoir 312, but each arm 310 is attached to the same medium 304. In some embodiments of the invention each arm 310 may be attached to an electrically separate medium 304. In some embodiments of the invention a first arm 315 via the fluid 311 in a first reservoir 316 may place a first receiver 317 into electrical communication directly with the core 306 while a second arm 318 via the fluid 311 in a second reservoir 319 may place a second receiver 320 into electrical communication with the conduit 309. This may allow for power to be sent down the core 306 and return via the conduit 309 or vice versa. The electrically conductive fluid 311 may comprise mercury, indium, an aqueous solution, liquid metal, gallium, eutectic mixtures, mixtures thereof, compositions thereof, or a combination thereof.

Referring now to FIGS. 3-5, as the swivel 201 is rotated the fluid 311 is retained within the reservoir 312 between the receiver 305 and the arm 310. The fluid 311 is also kept away from contact the rotary seals 313. This is accomplished by the rigid shape 314 of the reservoir 312. In the present embodiment the rigid shape 314 comprises a generally cylindrical geometry that is coaxial with the body 301. Both the reservoir 312 and the body 301 share a common central axis 321. The reservoir's rigid shape 314 also comprises inner and outer diameters 401, 402. The electrically conductive fluid 311 may flow along a length 403 of the reservoir 312 between the inner and outer diameters 401, 402. In FIG. 4 the swivel 201 is rotated 45 degrees from the position of the swivel 201 in FIG. 3. Whereas in FIG. 3 the reservoir's central axis 321 and an upper surface 404 of the fluid 311 were generally parallel to the ground 405 (see FIG. 1), in FIG. 4 the fluid's upper surface 404 is parallel to the ground 405 but the axis 321 is not parallel with the ground 405. The fluid 311 i retained within the reservoir 312 between the receiver 305 and the arm 310. The fluid 311 is retained away from the seals 313 both when the central axis 321 of the reservoir 312 is parallel with the ground 405 and when it is not parallel. Pooling contact of electrically conductive fluids with the seals 313 may lead to some electrically conductive fluid escape from the swivel 201 or faster degradation of the seals 313. In embodiments, where the electrically conductive fluid comprises mercury, escape of the electrically conductive fluid may hazardous to the environment or health of the drill rig operator.

In FIG. 5 the swivel 201 is rotated 90 degrees from the position of the swivel 201 in FIG. 3. The upper surface 404 of the fluid 311 is still parallel to the ground 405, but the central axis 321 of the reservoir 312 is now perpendicular to the ground 405. The fluid 311 is still retained within the reservoir 312 between the receiver 305 and the arm 310 and away from the seals 313. Also disclosed in FIG. 5 the rotary seals 313 may comprise o-rings 501. O-rings 501 may help to hold the seals 313 in place during rotation of the medium 304 within the swivel 201. In some embodiments of the invention at least one rotary seal 313 may comprise at least one o-ring, gasket, adhesive, washer, fastener, or combinations thereof. Springs or bearings 502 may be disposed within the body 301. Bearings 502 may assist with the connection of the body 301 with the NPT connector 207. Springs may include wave springs, Belleville springs, coiled springs or combinations thereof.

Referring now to FIG. 6, a cross-sectional diagram of swivel 201 discloses a first arm 315 in a first reservoir 316. A first receiver 317 is in electrical communication with the core 306 via the electrically conductive fluid 311 and the first arm 315. The electrical communication is connected to surface equipment (not shown) by a conductor body 601 which contacts the SMA connector 204. In some embodiments of the invention the first receiver 317 may receive a first signal carried up the medium 304, and the second receiver 320 may receive a second signal carried up the same medium 304. In such embodiments the first signal may be carried through the core 306 and the second signal may be carried through the conduit 309.

FIGS. 7-8 disclose alternative shapes 314 for reservoirs 312. The reservoir 312 in FIG. 7 comprises a generally cylindrical geometry that is generally coaxial with the body 301. The reservoir 312 comprises an outer diameter 402 along its entire length 403, but only comprises an inner diameter along a distal portion 702 of length 403. The arm 310 extends radially outward from the medium 304, and then turns in only one direction and becomes roughly parallel with the medium 304. FIG. 7 also discloses an arm 310 with an end 701 with a generally circular profile. In FIG. 8 a reservoir 312 is disclosed comprising a generally curved geometry. The curved reservoir 312 is closed on opposite ends 801, 802 of the reservoir 312. The arm 310 similarly comprises a generally curved geometry. A curved geometry may increase the amount of contact surface area between the arm 310 and the fluid 311 regardless of the orientation of the swivel 201. A portion 802 of the body 301 may comprise electrically conductive material. This portion 802 may be a receiver 305.

FIG. 9 discloses a reservoir 312 comprising a flow restrictor 901 proximate the rotary seal 313. The reservoir 312 also comprises a reservoir branch 902 that extends from the main volume 903 of the reservoir towards the medium 304. Fluid 311 may be restricted from greater contact with the rotary seals 313 by pooling fluid 311 in the branch 902 and by placing flow restrictors 901 proximate the seals 313.

Referring now to FIG. 10, a reservoir 312 may comprise an internal separator wall 1001. The wall 1001 may be attached to the reservoir 312 at a centre point 1002 and taper outward to extend along most of the length 403 of the reservoir 312. A portion of the electrically conductive fluid 311 is disposed on an inner side 1003 of the wall 1001 and a portion of the fluid 311 is disposed on an outer side 1004 of the wall 1001. When the swivel 201 is rotated, the fluid 311 on the outer side may be retained from contact with the rotary seals 313 by the wall 1001. A radial extension 1005 of the arm 310 may increase contact surface area between the arm 310 and the fluid 311. The extension 1005 may also ensure electrical communication of the receiver 305 and the medium 304 when the swivel 201 is orthogonal to the diagram disclosed in FIG. 10. One or more channels 1006 may extend from a first end 1007 of the reservoir 312 to a second end 1008 of the reservoir 312. This may direct fluid 311 away from the rotary seals 313 and discourage overflow of the fluid 311 onto the seals 313. In some embodiments of the invention a channel 1006 may extend from a first reservoir 316 to a second reservoir 319.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention. 

1. A swivel for use in a downhole drilling operation, comprising: a body comprising a central bore adapted for threaded connection to a tool string component; at least one electrically conductive medium rotationally supported within the bore and adapted to rotate with respect to an electrically conductive receiver that is rotationally fixed to and disposed within the body; the electrically conductive medium and the receiver being in electrical communication through an electrically conductive arm that is rotationally fixed to the electrically conductive medium and at least partially disposed within an electrically conductive fluid disposed within a reservoir; the reservoir comprising a rigid shape that is partially filled by the electrically conductive fluid; at least one rotary seal disposed intermediate the reservoir and the electrically conductive medium; wherein the rigid shape is adapted to prevent the conductive fluid from accumulating around the rotary seal.
 2. The swivel of claim 1, wherein the reservoir is disposed circumferentially around at least a portion of the at least one electrically conductive medium.
 3. The swivel of claim 1, wherein a channel extends from a first reservoir to a second reservoir or to a second end of the first reservoir.
 4. The swivel of claim 1, wherein the receiver is in electrical communication with an electrical device.
 5. The swivel of claim 4, wherein the electrical device is a computer, a data processing unit, a data storage unit, or combinations thereof.
 6. The swivel of claim 1, wherein the electrically conductive fluid comprises mercury, indium, an aqueous solution, liquid metal, gallium, eutectic mixtures, mixtures thereof, compositions thereof, or a combination thereof.
 7. The swivel of claim 1, wherein the swivel comprises a plurality of reservoirs.
 8. The swivel of claim 1, wherein the swivel comprises a plurality of electrically conductive arms.
 9. The swivel of claim 1, wherein an electrically conductive shield of a coaxial cable is in electrical communication with a first reservoir and an electrically conductive core of the coaxial cable is in communication with a second reservoir.
 10. The swivel of claim 1, wherein the electrically conductive medium comprises a coaxial cable, a pair of twisted wires, a biaxial cable, a triaxial cable, insulated copper wires, or combinations thereof.
 11. The swivel of claim 1, wherein the electrically conductive medium comprises an electrically conductive core surrounded by a dielectric material selected from the group consisting of alumina, ferrite, polycrystalline diamond, carbon, polymers, plastics, rubber, latex, and/or oxides of Mg, Al, Si, Yb, Ca, Be, Sr, Ns, Sm, Er, Eu, Sc, La, Gd, Dy, Tm, ceramics, and combinations thereof.
 12. The swivel of claim 1, wherein the at least one rotary seal comprises at least one o-ring, gasket, adhesive, washer, fastener, or combinations thereof.
 13. The swivel of claim 1, wherein the swivel comprises a plurality of electrically conductive media.
 14. The swivel of claim 1, wherein the rigid shape comprises a generally cylindrical geometry that is coaxial with the body and comprises inner and outer diameters.
 15. The swivel of claim 1, wherein the receiver is an electrically conductive portion of the body.
 16. The swivel of claim 1, wherein a volume of the reservoir is less than 50% full with the electrically conductive fluid.
 17. The swivel of claim 1, wherein the reservoir comprises an internal separator wall.
 18. The swivel of claim 1, wherein the reservoir comprises a flow restrictor proximate the rotary seal.
 19. The swivel of claim 1, wherein the rigid shape of the reservoir is adapted to retain the conductive fluid within the reservoir between the receiver and the electrically conductive arm and away from the at least one rotary seal when an central axis of the reservoir is parallel to the ground and when it is not parallel to the ground.
 20. The swivel of claim 1, wherein the swivel is in electronic communication with a downhole telemetry system. 